Tainted romaine circulation, Officials with the Centers for Disease Control and Prevention said they believe E. coli-tainted romaine lettuce blamed for more than 170 illnesses in 32 states is likely no longer in circulation.

The current outbreak has been traced to the Yuma, Arizona growing region.

“According to the U.S. Food and Drug Administration, the last shipments of romaine lettuce from the Yuma growing region were harvested on April 16 and the harvest season is over. It is unlikely that any romaine lettuce from the Yuma growing region is still available in stores or restaurants due to its 21-day shelf life,” the CDC said in its latest advisory.

It takes two or three weeks between when a person becomes ill with E. coli and when the illnesses are reported to the CDC.

“The most recent illnesses reported to CDC started when romaine lettuce from the Yuma growing region was likely still available in stores, restaurants, and in peoples’ homes,” the agency said.

The lettuce currently being harvested is coming from California.

As of the May 15 update, 172 people have been sickened in the outbreak, an increase of 23 people and three states since the last update. One death and 75 hospitalizations have been reported. Three new states – Iowa, Nebraska and Oregon – reported cases last week. No cases have been reported in Alabama.